The use of restressed concrete finished parts, in comparison with erecting towers or pylons with a climbing or sliding concrete form or sheathing, has the advantage of an economically more favorable possible way of producing the finished parts, under predetermined conditions. In that way, a large part of the work involved can already be carried out far from the building site. In addition it is in that way better possible to satisfy predetermined quality requirements and to monitor the procedure to ensure that such requirements are met, and the pylon can then be erected on the building site in a short time.
For that purpose the prestressed concrete finished parts are assembled with jacket tubes, incorporated into the pylon wall, for the tensioning means, on the building site. In that case, to connect the individual finished parts together as segments of the pylon, a concrete mix is introduced into the joins between the segments in order to achieve a force-locking connection, over a surface area, between the finished parts. The tensioning means which are pulled into the jacket tubes are then tensioned and thereafter the jacket tubes are filled with a concrete slurry under high pressure and pressed in order to produce an intimate connection between tensioning means and pylon.
The operation of pressing the tensioning means in the jacket tubes must be effected under high pressure so that the concrete slurry can rise in the jacket tubes and fill them to the tip of the pylon, with the required pressure. That required pressure can certainly attain values of 200 bars, in the case of pylons which are 80 m high. In that respect it will be noted that the state of the art involves the problem that the concrete slurry which is under high pressure can escape at the junctions between the individual segments as the concrete therebetween is brittle and porous as a consequence of its material properties and therefore the transition between the segments is not reliably sealed off.
Therefore it may be necessary to provide an access for the injection of the concrete slurry, beginning with the lowermost segment and moving upwardly on the tower, at each junction between mutually superposed segments, and to feed the concrete slurry at such access points in order to press the jacket tubes of the respective segment disposed thereabove.
In Germany tensioning bars and tensioning wires are considered as tensioning means. The use of tensioning bars however is subject to the limitation that they can be used exclusively when dealing with straight tensioning paths. This means however that the options in terms of the contour of a tower comprising prestressed concrete finished parts are limited when using tensioning bars as they always have to be in a straight line. This means that the erection of a conical pylon with tensioning bars is possible as long as the cross-section of the pylon tapers in a rectilinear configuration.
Therefore only the use of a tensioning wire is considered for the purposes of erecting a conical pylon with a curved contour. The tensioning wire is pulled in either from the tip of the pylon into the jacket tubes of the segments continuously down to the base of the pylon or from the base of the pylon continuously up to the tip of the pylon. That procedure however suffers from the problem that the tensioning wire, from the tip of the pylon to the base region thereof along the curved contour, has to pass over the junctions between the individual segments. As a consequence of the curvature however, there is always the danger that the wire does not follow the curvature in particular at such a junction, but becomes jammed at the junction and can be moved along only at great cost.